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Thursday, December 31, 2009

Verification for Wednesday: I expected mostly sunny skies with high temperatures in the upper 20s to lower 30s northwest of NYC, and in the lower to mid 30s for NYC and closer to the coast. My high temperature northwest of NYC was in the lower 30s, and for NYC high temperatures were in the lower to mid 30s, so my forecast verified.

Verification for Wednesday Night: I expected increasing clouds with low temperatures in the lower to mid 20s northwest of NYC, and mid to upper 20s for NYC and closer to the coast. Temperatures however did not drop much overnight, with temperatures remaining in the upper 20s to lower 30s for NYC, and further away from NYC temperatures were into the mid to upper 20s. So my forecast was a bit too cold, but overall not too far away from the actual results.

Today: Cloudy. Snow, heavy at times, falling until 1 PM, then scattered snow showers, mixing with rain near the coast. High temperatures will be in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast. Snow accumulations will be between 1 and 3 inches, with the higher totals the further north you go.

Tonight: Cloudy. Scattered rain and snow showers. Low temperatures will be in the mid to upper 20s north and west of NYC, and in the lower to mid 30s for NYC and closer to the coast.

Tomorrow: Cloudy. Scattered rain showers, with snow showers mixing in the morning north and west of NYC. High temperatures will be in the upper 30s north and west of NYC, and in the lower 40s for NYC and closer to the coast.

Tomorrow Night: Cloudy. Scattered snow showers. Low temperatures will be in the lower to mid 20s north and west of NYC, and in the mid to upper 20s for NYC and closer to the coast.

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Longer Term Update:

The issue for the second storm has been resolved as of last night, and the second storm should not affect us with anything more than cold, wind and scattered snow showers. While places from Boston and further north and east could get a lot of snow with that storm, we will stay far away from it to only get mostly cloudy skies and scattered snow showers. Conditions will also become increasingly windy for Saturday and Sunday, with high temperatures in the 20s to lower 30s across the area. Temperatures will begin warming a little on Monday into the upper 20s to 30s, and should stay there for most of the week. Then attention will turn to late next week into early next weekend, when the next possibility for another storm exists.

It's currently snowing heavily here in Bergen County, northwest of New York City. It was barely snowing for 30 minutes and there is already 0.5 inch of snow on the ground. This however appears to be a quick mover, and combined with a dry slot in southeastern Pennsylvania that will lead to the snow ending earlier, the snow will likely end within a few hours with no changeover to rain, leaving us with 1-3 inches of snow, with higher totals the further north you go.

Forecast for Tuesday: I originally expected high temperatures to be in the low 20s north and west of NYC, and in the mid 20s for NYC and closer to the coast. While the actual 24 hour highs peaked around midnight in the upper 20s to low 30s, the mid day high temperatures were in the upper 10s inland, lower 20s for NYC and the closer suburbs, and mid 20s near the coast, so verification was not so bad.

Verification for Tuesday Night: I expected low temperatures to be in the upper single digits to lower 10s north and west of NYC, and in the mid to upper 10s in NYC and closer to the coast. While most of the interior area away from NYC did not see lows below 10 degrees, low temperatures were in the low 10s north and west of NYC, and in the mid 10s for NYC. Both of these lows were in the range of my forecast, so my forecast also verified well.

Today: Mostly Sunny skies. High temperatures will be in the upper 20s to lower 30s north and west of NYC, and in the lower to mid 30s for NYC and closer to the coast.

Tonight: Increasing Clouds. Low temperatures will be in the lower to mid 20s north and west of NYC, and in the mid to upper 20s for NYC and closer to the coast.

Tomorrow: Cloudy. A few snow showers will start for the area, changing over to light rain for the coast, a mix of rain and snow for NYC and its suburbs, with a snow and sleet mix north and west of GSP/I-87 (Garden State Parkway, Interstate 87). High temperatures will be in the mid 30s north and west of GSP/I-87, and in the mid to upper 30s elsewhere except for the coast, in the upper 30s to lower 40s. A light snow and sleet accumulation is possible.

Tomorrow Night: Cloudy. Scattered rain showers, mixing with snow north and west of GSP/I-87. temperatures will be in the in the upper 20s to lower 30s north and west of NYC, and in the lower to mid 30s for NYC and closer to the coast.

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The poll for the prediction of the New Year's Storm has closed. Below are the final results, out of a total of 39 votes:

There is still a lot of uncertainty about this storm, however we are slowly starting to get an idea of what could happen with the first part of the storm. This storm is currently expected to come in two waves, the first one on Thursday and the second one on Friday, with a lull in precipitation possible overnight on Thursday. The first storm will come when some of the cold is still in place, however it will remove the cold air. Precipitation may start as virga at first, meaning precipitation that is falling in the air and not reaching the ground, due to the low dew points, however any precipitation to start should be in the form of snow showers. Afterwards, we see a transition to rain near the coast, with a wintry mix for NYC and closer areas, with mainly snow and sleet for the interior. This is going to be a quick event, with any precipitation falling generally being light to occasionally moderate, with the interior areas possibly picking up a light accumulation of snow and sleet.

For the second part of the storm on Friday, there is still too much uncertainty to be able to make a clear forecast. Unfortunately, the forecast models are having issues handling the second storm, and they may not agree on a solution until the storm is already reaching the area. In this case, we would need to look at the actual observations, compare it to the forecast models, and see if there are any differences and what that might mean for the forecast. Stay tuned for further updates to be made tomorrow or possibly later today.

Long Range Update: After this storm, it's going to turn cold again. for Saturday, scattered snow showers are possible, with both Saturday and Sunday having windy conditions and highs in the 20s, Sunday being the colder day. By the early week, temperatures might warm a little into the 30s, and by late next week, the forecast models are hinting at another storm that might affect the area.

Tuesday, December 29, 2009

For my forecast verification from yesterday, I expected highs to be in the upper 30s to low 40s. The result highs were in the low 40s for the NYC metro including NE NJ, and further inland towards Orange County, NY and Passaic County, NJ, highs were in the upper 30s, so my forecast was correct. Scattered rain/snow showers were also reported to the north of NYC.

For the overnight verification, I expected lows overnight to be in the mid-upper 10s northwest of NYC, and upper 10s to low 20s for NYC and closer to the coast. The actual lows also followed the forecast, with the airports in NYC reporting lows in the low 20s, and airports further inland reporting lows in the mid to upper 10s.

Today: Mostly Sunny skies and windy. Very cold. High temperatures will be in the low 20s north and west of NYC, and in the mid 20s for NYC and closer to the coast. Wind chills will be in the single digits to lower 10s all day.

Tonight: Mostly Clear skies. Low temperatures will be in the upper single digits to lower 10s north and west of NYC, and in the mid to upper 10s for NYC and closer to the coast.

Tomorrow: Mostly Sunny skies. High temperatures will be in the upper 20s to lower 30s north and west of NYC, and in the lower to mid 30s for NYC and closer to the coast.

Tomorrow Night: Increasing Clouds. Low temperatures will be in the lower 20s north and west of NYC, and in the mid to upper 20s for NYC and closer to the coast.

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New Year's Day Storm:

This is where things get interesting again. Yesterday, I made a scenario map and said how this does not look like a mainly snow event for NYC. In fact, the forecast weather models still remain with a rain to snow solution for the area, however the coastal low has trended slightly further east than previous runs but still intensifies at about the same latitude, meaning we would get light rain to snow showers with light QPF amounts, with the storm intensifying at a location that would blast northern New England with the highest amounts of snow. It would be easy to say that this will be the final solution for this storm, however that would be following exactly what the models show, which is not very good considering how frequently they change. For that we have to look at the trends and the pattern, and what this might tell about this storm.

What we do know at this time is that there will be a storm, it will rapidly intensify and stall at some point, and there is also going to be a weak area of low pressure in southern Canada that will prevent the cold air from taking over at first. We have seen the forecast track by the models anywhere between along the immediate coast line to way offshore, giving us a wide range of possibilities. However, there is a general agreement that the storm will only begin to rapidly intensify after it passes the area, which would be too late for us to receive any significant precipitation. This is also when the cold is drawn in once the storm intensifies, meaning that with this solution, we would see scattered snow showers with very cold temperatures after this storm.

It is too early to know specific details at this time due to the uncertainty, however what we do know at this time is that the NYC tri-state area is likely to see both rain and snow, starting out as rain and then changing over to frozen precipitation. Once the strength of the storm and its location become clearer, it will then be easier to find out how much rain and snow we will get and the amount of time spent before the changeover to frozen precipitation.

For now, I continue with the expectation that NYC starts out with rain on Thursday afternoon, changes over to snow sometime on Friday, and then sees scattered snow showers into Saturday. Coastal areas will see mainly rain with snow showers at the end of the storm, and areas further inland (Orange NY/Passaic NJ counties and further north/west) will see a period of rain/mix changing over to mainly snow. The entire area could see windy conditions on Saturday and Sunday.

Long Range Update: Regardless of the storm and which scenario happens, it's going to get cold afterwards. Sunday will be the coldest day with highs in the 20s again, and combined with the possible windy conditions, wind chills could go back into the single digits. Temperatures then moderate into the 30s to start next week.

Now onto the storm. Several days ago, weather forecasting models such as the GFS and Euro showed a giant snowstorm for the area, which if happened, would produce near blizzard conditions across the Interstate 95 corridor and heavy snowfall. However, since then, there has been a change in the forecast, and the weather models began trending further north and west with the location of this storm. Now, most of the models have trended far west enough with this storm that coastal locations would see mainly rain from the solutions that the models have. This westward trend is typical with storms that are in the long range, as so far this winter, most of the storms that have affected us were shown to be further east than they actually were about a week prior to the storm affecting the region. This storm proved to be no different. The latest run of the NAM (12z run) had a completely different scenario and took this storm out to sea, which proves that there is still a great deal of uncertainty and that we will have to wait until at least late Tuesday/Wednesday before we have a better idea of what happens, which is why this is only a generally low confidence preliminary discussion/map.

Remember that this is only a preliminary scenario map, there are still a few days until this storm reaches the area, and things can still change. Do not consider this as the final solution.We will first see a coastal low moving north northeast from the eastern part of North Carolina, staying close to the coast. However, we are not looking at the cold air to immediately take over, as there will be a weak low pressure area in the Great Lakes that will prevent that from happening at first. As a result, the coastal low will start out mainly warm, with rain starting from the coast and reaching as far west as up to 50 miles west west of the I-95 corridor. Areas further west than that will start out with a snow or a wintry mix.

The storm is then expected to rapidly intensify, and then slow down or nearly stall. By this time, which should be later on Friday, the storm will be able to draw in cold air, with the rain/snow line moving further east. The question is, where will the storm slow down and/or stall, as it is very important in finding out how much snow we get. I am thinking at this time that it happens in western Massachusetts, which combined with the entering cold, would mean that the area will then change over to snow. However, we would not see a significant snowfall, but rather a lighter snowfall, with a wintry mix possible for western Long Island and eastern Long Island staying all rain. The storm will then begin to weaken, with precipitation ending on Saturday.

Different Possible Scenarios: As I said before, this is only a preliminary scenario map, and there are still several different solutions that have to be considered:1. The storm manages to phase and intensify earlier, resulting in a brief rain to a prolonged snow event for the area.2. The storm continues to trend west and becomes warmer, resulting in mainly rain to a mix for the area.3. The storm trends a little more south and east, resulting in a snowier solution for the area.4. The storm ends up intensifying too far east, resulting in scattered rain/snow showers for the area.

Now for the details about the map:

Green zone: Mainly rain, possibly changing to light snow showers at the end for the northern half of this region (from the Jersey Shore to Cape Cod).

I am splitting today's update into two parts, one of them is this part about the short term forecast, and then I'll do a discussion and scenario map for next weekend's storm.

Below is my forecast verification from Saturday:

I did not do very well for Saturday night, because I expected temperatures to drop overnight, which did not happen. As it became likely that temperatures would continue rising, I updated my forecast to expect steady temperatures in the upper 40s to low 50s, however that was still too low. Temperatures across the region peaked in the low to mid 50s early Sunday morning, afterwards the temperatures dropped several degrees and stayed steady most of the day. For Sunday night's forecast, the forecast verified better. Lows in Bergen County were in the upper 20s to mid 30s, and low to mid 30s in NYC, which is close to what I expected in my forecast.

Today: Cloudy skies becoming partly cloudy. A few rain/snow showers ending in the morning for southeastern New York (From Rockland county and further north). Temperatures will rise into the upper 30s to lower 40s across the region, then begin to fall in the late afternoon hours.

Tonight: Mostly Clear skies, with windy conditions possible at times. Low temperatures will be in the mid to upper 10s north and west of NYC, and in the upper 10s to low 20s for NYC and closer to the coast.

Tomorrow: Mostly Sunny skies and windy. Very cold. High temperatures will be in the low 20s north and west of NYC, and in the low to mid 20s for NYC and closer to the coast. Wind chills will be in the single digits to lower 10s all day.

Tomorrow Night: Mostly Clear skies. Low temperatures will be in the lower 10s north and west of NYC, and in the mid to upper 10s for NYC and closer to the coast.

Saturday, December 26, 2009

High temperatures in Bergen County, northwest of NYC were in the upper 30s, with NYC near 40 degrees, which followed my forecast. Lows overnight were mainly steady and started rising after midnight, from the mid to upper 30s, which I correctly forecasted the temperatures but did not mention that they were going to rise.

Tonight: Mostly Cloudy skies with rain ending in the evening hours. Low temperatures will be steady in the mid to upper 40s northwest of NYC and in the upper 40s to lower 50s near NYC and closer to the coast.

Tomorrow: Mostly Cloudy skies. Highs will be in the mid to upper 40s northwest of NYC, and in the upper 40s to lower 50s near NYC and closer to the coast. Temperatures will start dropping early in the afternoon.

Tomorrow Night: Cloudy skies with areas of light snow after midnight, mixing with rain near the coast. Lows will be in the upper 20s to lower 30s northwest of NYC, and in the low to mid 30s near NYC and closer to the coast. A dusting of snow is possible in the higher elevations further north and west.

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5-Day Forecast Update: Tomorrow will be a very nice day across the area, with highs breaking the 50 degree mark in some areas closer to the coast. But enjoy tomorrow while you can, because afterwards, things get colder. It appears that we are likely going to see snow showers to start Monday, with a light dusting of snow possible further inland, away from NYC. After this snow ends, temperatures begin rapidly dropping, with overnight lows dropping below 20 degrees north and west of NYC. Tuesday will be the coldest day yet, with highs in the mid to upper 20s for NYC, and low to mid 20s further north and west. Wednesday will still be very cold, with NYC and areas closer to the coast briefly reaching the 30 degree mark.

New Year's Day Storm?As I mentionedyesterday, there is the threat of a storm for New Year's Day. The models are still showing the storm, with a few models even showing a full blown blizzard for the area. The pattern will certainly be favorable for a storm to affect the area, and the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO), which when negative can favor a cold pattern over the East Coast, will be negative, can also suggest that the storm is unlikely to track too close to bring plain rain to the area.

My current take on this time frame is that Thursday will have highs in the upper 20s to mid 30s with snow and rain approaching from the southwest, and the worst part of the storm will be on Friday, even though that may change as there are still timing issues with the storm. The storm will likely start out with mainly snow, though we may get mixing on Friday. It is still too early to determine which area gets what kind of precipitation, though when the forecast for this storm becomes clearer I will make a scenario map for this storm. Stay tuned for further updates on this potential snowstorm.

Friday, December 25, 2009

To start off with my first forecast, below is my forecast for today and tomorrow in the area. In some cases, such as today, I use the Garden State Parkway and I-87 in southeastern NY as the dividing line for different types of weather, which is referred to as northwest or southeast of GSP/I-87.

Today: Cloudy skies are expected across the area, with a few showers possible after 2 PM. High temperatures will be in the upper 30s to lower 40s across the area.

Tonight: Periods of rain, mainly after midnight. Freezing rain will fall north and west of GSP/I-87. Low temperatures will be steady in the mid to upper 30s near NYC, and in the low 30s further inland. Rainfall amounts will be between a quarter and a half of an inch.

Tomorrow: Rain, heavy at times. Freezing rain may mix before 9 AM northwest of GSP/I-87. High temperatures will be in the upper 30s to low 40s north and west of GSP/I-87, low to mid 40s for the immediate north and west suburbs of NYC, and mid to upper 40s for NYC and areas closer to the coast. Rainfall amounts will be between a half and three quarters of an inch.

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5-Day Forecast Update: An intense storm currently located far to our west will impact our area until late tomorrow night. Precipitation will enter the area late this afternoon to the early evening hours, and intensify throughout the night. Further inland away from New York City, it will be cold enough for freezing rain to fall, with ice amounts between 0.1 and 0.2 inch, enough to cause dangerous road conditions. As the storm pulls warmer air into the area, any freezing rain will change over to rain by tomorrow morning, with temperatures rising into the 40s except for the interior areas in the higher elevations. There is the potential for some flooding, as the heavy rain will melt most of the remaining snow cover from last weekend's snowstorm. After falling heavy at times tomorrow, the rain will taper off tomorrow night, with total rainfall amounts generally near an inch, locally near two inches.

A risk of showers remains on Saturday with mostly cloudy skies, however temperatures will be unusually mild, in the mid to upper 40s. Locations closer to New York City may even reach 50 degrees. Light snow could possibly develop on Sunday night and Monday, however very little accumulation will be seen with this potential light snow event. Monday will then begin the transition to colder weather, with highs only in the mid to upper 30s. In fact, overnight temperatures continue to drop even more into the 10s for the interior and 20s elsewhere. Tuesday will be the coldest day of the week, with highs only in the mid to upper 20s. Coastal locations may briefly reach 30 degrees.

Long Range Update: Temperatures through the week will remain cold, however temperatures will moderate some, with highs back into the 30s. Late next week, a weak storm is expected to develop in the South and head out to sea, but that's not the end of it. Another storm, stronger than the first one, may then develop on New Year's Day, and the upcoming pattern by that time period (neutral to positive PNA, -NAO and -AO) will be favorable for this storm to affect the area, possibly in the form of snow. There is still uncertainty on this storm, however it is a time period to keep an eye on. Stay tuned.

Welcome to my NYC weather blog. For the avoidance of doubt, I am not a meteorologist, forecasting weather is a hobby for me and I make weather forecasts for the New York City tri-state area, including the suburbs. I usually make my forecasts in a format where I enter yesterday's observations for the area, followed by a detailed forecast for that day and the following day, followed by a 5-day discussion with an update on the longer range. Sometimes I may also add pattern outlooks.

Thank you for visiting my weather blog. Appropriate and subject relevant comments are welcome and I will take some into consideration when making updates.